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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Species composition and geographic distribution of ticks infesting cattle, goats and dogs in Maputo Province, Mozambique

Matos, Carlos Antonio de 20 February 2009 (has links)
The primary objective of this study was to determine the species composition of ticks that infest domestic animals in Maputo Province and their geographic distributions. To this end a total of 145 cattle, 129 goats, 132 dogs and 63 drag­samples of the vegetation were examined at 30 localities distributed throughout the province, at each of which the geographic coordinates were recorded and later plotted. A total of 15187 ixodid ticks belonging to 15 species were recovered. These were Amblyomma hebraeum, Haemaphysalis elliptica, Haemaphysalis sp., Hyalomma rufipes, Ixodes cavipalpus, Rhipicephalus (Boophilus) microplus, Rhipicephalus appendiculatus, Rhipicephalus evertsi evertsi, Rhipicephalus kochi, Rhipicephalus longus, Rhipicephalus pravus group, Rhipicephalus sanguineus, Rhipicephalus simus, Rhipicephalus tricuspis and Rhipicephalus turanicus. R. (B.) microplus and A. hebraeum were most abundant on cattle, while H. elliptica was most abundant on dogs. H. elliptica, I. cavipalpus, R. longus and R. turanicus can now be added to the lists of ixodid tick species previously published for Mozambique. The geographic distributions of nine of the 15 tick species were mapped, and A. hebraeum, H. elliptica and R. evertsi evertsi were present throughout the province. No indigenous Rhipicephalus (Boophilus) decoloratus were recovered, whereas the introduced Asian tick, R. (B.) microplus was present in all districts. It would seem that R. (B.) decoloratus has been completely displaced by R. (B.) microplus in Maputo Province. Although R. appendiculatus was recovered at 24 of the 30 localities, it was present at only two of the seven localities in the south of the province. R. sanguineus was present on dogs in the districts of Boane, Naamacha and Manhiça, where the collections were made at the dog owners’ homes. R. simus was present at 27 localities and R. turanicus was collected in the districts of Magude, Boane, Namaacha and Matutuine, in the north, centre and south of the province. Future surveys in Mozambique should focus on determining the extent to which R. (B.) microplus has displaced R. (B.) decoloratus. A further objective of the study was to compare the prevalence of the five major tick species, namely A. hebraeum, R. (B.) microplus, R. appendiculatus, R. evertsi evertsi and R. simus on cattle and goats. It was possible to do this at 21 of the sampling sites, at each of which five cattle and five goats had been examined. These five ticks infested both cattle and goats, but the goats harboured larger numbers of immature ticks and fewer adults of some species, while large numbers of both adult and immature ticks were recovered from cattle. Furthermore, more cattle than goats at more localities were infested with adult ticks of each of the five species. Consideration should be given to including goats in future tick control programmes applied to cattle on the same properties. A total of ten ixodid tick species were recovered from dogs in Maputo Province. Of these H. elliptica, R. sanguineus, R. simus and R. turanicus can be considered major parasites of dogs, while large numbers of immature A. hebraeum and smaller numbers of immature R. appendiculatus infested these animals opportunistically. / Dissertation (MSc)--University of Pretoria, 2008. / Veterinary Tropical Diseases / unrestricted
32

Etableringsmomentets inverkan på växtsamhällets artdiversitet - Har uppvärmning någon effekt? / The Impact of the Establishment Moment on the Species Diversity of the Plant Community - Does Warming have an effect?

Juhlin Eriksson, Elin January 2023 (has links)
The aim of this study was to assess how the plant community and its species diversity are affected by establishment methods and warming. Priority effects, i.e., the order of species arrival in plant establishment, are an important subject when invasive species become more common, and the biodiversity decreases as the global temperature continues to increase. A field experiment was carried out to investigate the effect of establishment methods and temperature on plant communities by using four different establishment methods. The plants were divided into two groups (fast and slow germinating) and sown at two occasions, one earlier than the other. Half of the study plots were then treated with OTC (Open Top Chambers) and the other half were used as control. There was a difference in temperature between the OTC blocks and the control blocks. OTC had no effect on the number of species or the Shannon diversity index but affected the proportion fast germinating, slow germinating, and naturally established species. There was a significant effect of the establishment events on the plant community. There was also a significant interaction between OTC treatment and establishment, only present for the proportion of fast germinating species. The temperature differences can provide information on plant responses to global warming and the results can mostly be explained by priority effects such as numerical superiority and competition in combination with germination rate are. The results of this study can be used to better understand how warming and priority effects may affect plant communities in the future.
33

Small Mammals in portions of Great Basin National Park Susceptible to Groundwater Withdrawal: Diversity and Stable Isotope Perspectives

Hamilton, Bryan T. 26 February 2009 (has links) (PDF)
To support population growth in Las Vegas, Nevada, large scale increases in groundwater pumping are planned across the state. This pumping could affect riparian areas in Great Basin National Park by lowering groundwater levels, reducing stream flows, and xerifying riparian vegetation. Great Basin National Park (GBNP) is mandated to manage its resources unimpaired for future generations. Loss of biodiversity is unacceptable under this mandate. If groundwater levels are reduced beyond a threshold, aquatic and riparian diversity would be lost, but the effects on small mammal communities are less clear. To provide baseline information and to consider the effects of groundwater withdrawal a priori, we sampled and compared small mammal communities in two watersheds susceptible to groundwater withdrawal and one non-susceptible watershed. We also used to stable isotopes of nitrogen, carbon, deuterium and oxygen to characterize small mammal communities. Evenness was higher in susceptible watersheds, which were distinct in species composition. Riparian and upland habitats in susceptible watersheds supported complementary small mammal communities, while communities in the non-susceptible watershed were more homogenous. Susceptible watersheds are located at the lowest elevations of GBNP where habitat heterogeneity due to the contrast between mesic riparian and xeric upland habitats is important in maintaining small mammal diversity. Partitioning was primarily seen in nitrogen and carbon isotopes which reflect feeding ecology (trophic level and primary production source), but was also seen in oxygen isotopes. Major differences in nitrogen and carbon isotopes were between taxonomic groups, while similarity was highest within these groups. Shrews and ermine were highest in nitrogen reflecting their high trophic positions. Harvest and piñon mice were intermediate in nitrogen suggesting omnivory, while chipmunks, voles, woodrats and pocket mice were apparently herbivorous. Carbon ratios were consistent with C3 based diets but were relatively enriched in Sigmodontinae species. Small mammal deuterium was similar to stream water suggesting that stream water is an important water source of water to small mammals. Oxygen enrichment relative to stream water and precipitation suggested that small mammals are sensitive to body water evaporation. Contrary to a previous study, oxygen isotopes were inversely related to water use efficiency. Increases in the rate of groundwater pumping adjacent to Great Basin National Park could lower water tables, reduce stream flows, and xerify riparian vegetation. We suggest that groundwater levels, streams flow and riparian vegetation, in addition to small mammal species composition will be important response variables in monitoring the effects of groundwater withdrawal. If predictions of groundwater withdrawal are realized, groundwater levels, stream flows, vegetation, microclimate, and invertebrates riparian dependent as well as small mammals will be negatively affected resulting in a decrease in diversity and loss of riparian species from affected areas.
34

Effekten på artsammansättning i växtsamhällen vid betning av Rangifer tarandus / The effect of Rangifer tarandus grazing on species composition in plant communities

Voss-Schrader, Emilie January 2023 (has links)
The fact that large herbivores, such as Rangifer tarandus, play a part in shaping its environment through grazing and trampling of the ground is widely acknowledged today, as well as that these factors have the potential of affecting regional patterns and even global climate. This study investigated whether a considerable increase in grazing by R. tarandus for 25 years resulted in any measurable effects on the diversity of plant species in tundra vegetation. We evaluated if any differences in species composition could be found, based on differences in grazing pressure and productivity of the soil. The effect of difference in grazing pressure was studied through analysis of vegetation at 30 sites, each site comparing two different classes of grazing pressure separated by a fence, and pellets from R. tarandus were counted along transects. We did not find any evidence that the difference in grazing pressure affected the species composition on either side of the fence, depending on the site. The lack of difference in plant species composition may be explained by insufficient differences in abundance of R. tarandus, insufficient time passed since the change in grazing pressure, or varying grazing seasons at the sites on either side of the fence.
35

An improved benthic survey method for coral composition and distribution: Habitat Reef, Curaçao

Sams, Erin E. 12 December 2012 (has links)
No description available.
36

Bats in Urban Sweden : A multiple regression analysis of bats’ relationship to urbanization

Andersson Skog, Nils January 2021 (has links)
Human development continues to use up more physical space in the natural world, threatening the natural habitats of many organisms. To combat the loss of biodiversity science needs to explore what landscape features are important for different organisms so that we can incorporate these into the modern environment. As bats play an important role in many ecosystems and can reflect changes through trophic levels, analyzing their preferred habitats can help planners improve biological diversity of the urban habitat. Using acoustically identified bat sightings from Artportalen.se for the years 2017-2018, this paper studied the habitats of bats in Sweden. Through multiple regression analysis we examine the response in abundance and/or diversity of bats to physical and socio-cultural attributes of the urban habitat. We examined a total of 10160 bats from 18 species in 418 land cover locales and 306 demographical statistical areas with varying degrees of urbanization. Our results indicate that bat abundance and diversity decrease significantly with higher urbanization while deciduous forests are the most important land cover type for all bats. The results also indicate that wealthier areas have less abundance and diversity even when factoring in population density. Species specific analysis suggested that bat species who are better adapted at foraging in open vegetated landscapes and over water were less susceptible to the negative impacts of the urban habitat. We conclude that diverse habitats with a mixture of open vegetated areas, watercourses and broadleaf forests are the most important land features for a diverse bat fauna along with high connectivity via tree cover and linear landscape elements. If urban planning could incorporate these features into the urban habitat, some of the negative impacts of urbanization could be prevented.
37

Sumedėjusios augalijos kaita Vištytgirio botaninio-zoologinio draustinio miško aikštėse / Changes in the woody vegetation of clearances in Vištytgiris botanical-zoological reserve

Panitauskaitė, Enrika 16 June 2014 (has links)
Magistro darbe tiriama sumedėjusios augalijos kaita Vištytgirio botaninio-zoologinio draustinio miško aikštėse. Darbo objektas – miško aikštelės Vištytgirio botaniniame-zoologiniame draustinyje. Darbo tikslas – nustatyti susidariusiose aikštėse sumedėjusios ir žolinės augalijos kaitą ir įvertinti mikroklimato įtaką Vištytgirio botaniniame-zoologiniame draustinyje. Darbo metodai – sumedėjusiai augalijai įvertinti naudojama juostinė transekta. Sumedėjusios augalijos žėlinių tankis vertintas iki 50 cm ir virš 50 cm. Žolinės augalijos projekcinis padengimas įvertinamas vizualiai, įvertinama, kokią paviršiaus dalį (procentais) dengia kiekviena žolinių augalų rūšis. Dirvožemio temperatūra ir drėgnumas nustatytas prietaisu „Wet“, o dirvožemio rūgštingumas prietaisu „PMT 3000“. Apšvietimas įvertintas aikštelėse ir po medžių lajomis prietaisu „Hemi View Canopy System“. Taikant sumedėjusios ir žolinės augalijos bei dirvožemio temperatūros, drėgnumo ir rūgštingumo taip pat apšvietimo vertinimo metodus, nustatyta ir įvertinta miško aikščių sumedėjusios augalijos kaita, bei ją įtakojantys mikroklimatiniai veiksniai skirtingo dydžio miško aikštėse. Darbo rezultatai. Tyrimo metu buvo įvertinta Vištytgirio botaninio-zoologinio draustinio miško aikščių sumedėjusios ir žolinės augalijos rūšinė sudėtis ir gausa. Mažose miško aikštėse nustatytos šešios savaiminukų rūšys, vidutinio dydžio – septynios, didelėse – penkios rūšys. Mažose aikštelėse vyravo šviesos trūkumą pakeliančios, vidutinio... [toliau žr. visą tekstą] / Changes in the woody vegetation of clearances in Vištytgitis botanical-zoological reserve are analysed in the work of master science. Object of the work – forest observation plots in Vištytgiris botanical-zoological rezerve. Aim of the research – to determine the changes of woody and herbaceous vegetation in stand clearings and to assess the impact of microclimate. Method of the work – to determine woody vegetation, strip transect was used. The density of woody vegetation was measured up to 50 cm and above 50 cm. Projection coveraged was determined visually. It was determined what surface (in percentage points) is covered by each species of herbaceous plants. Soil temperature and moisture content were determined using device “Wet“ and soil acidity with device “PMT 3000“. Lighting was measured in each plot and under the trees crown using the device “Hemi View Canopy System“. Using woody and herbaceous vegetation and soil temperature, moisture content and acidity as well as lighting assessments methods to identified and evaluated vegetation changes and influencing factors in formed forest clearances. The results of the work. After the research in Vištytgiris botanical-zoological reserve was evaluated woody and herbaceous vegetation species composition and abundance in forest plots. In small forest plots were determined 6 species of natural regeneration, in medium-sized forest plots – 7 and in large – 5 species. In small plots dominated tree species, which is not demanding to... [to full text]
38

The impact of forest on pest damage, pollinators and pollination services in an Ethiopian agricultural landscape

Samnegård, Ulrika January 2016 (has links)
The distribution of wild biodiversity in agroecosystems affect crop performance and yield in various ways. In this thesis I have studied the impact of wild biodiversity, in terms of trees and forest structures, on crop pests, pollinators and the pollination services provided in a heterogeneous landscape in southwestern Ethiopia.  Coffee, Coffea arabica, is a forest shrub native to Ethiopia and is grown in most wooded areas in the landscape where I conducted my studies. Wild coffee is still found in remote parts of the forests in the landscape. For my first paper, I surveyed pest damage on coffee in coffee forest sites, where some sites were situated in continuous forest and some in isolated forest patches. I found the variation in pest damage frequency to mainly be among coffee plants within a site, rather than among sites, which indicates the importance of local processes. However, some pests were clearly connected to the forest habitat, such as the olive baboon. In my second study, I surveyed pollinators visiting coffee flowers across a gradient of shade-tree structures. I found the semi-wild honeybee to be the dominating flower visitor. The abundance of the honeybee was not related to shade-tree structures, but to amount of coffee flower resources in the site. On the other hand, other pollinators, which included other bee species and hoverflies, were positively affected by more shade trees in the site. In my third study I investigated how the forest cover affected local bee communities in the agricultural landscape. Moreover, I investigated if this relationship differed between the dry and rainy season. The distribution of food resources for bees changes between the seasons, which may affect the bees. Most trees, fruit trees and coffee, which are patchy resources, flowers in the dry season, whereas most herbs and annual crops, which are more evenly spread resources, flowers during the rainy season. I found a clear turnover in bee species composition between the dry and rainy season, with more mobile species in the dry season. Increased forest cover in the surrounding landscape had a positive impact on bee abundance and species richness. However, the impact did not change between seasons. In my fourth study I evaluated the pollination success and pollen limitation of a common oil crop in the landscape in relation to forest cover. I found severe pollen limitation across the landscape, which may be related to the observed low bee abundances. The pollen limitation was not related to surrounding forest cover. In conclusion, I have found the forest and wooded habitats to impact several mobile animals and pathogens in our study landscape, which in turn affect people. However, there is large complexity in nature and general relationships between forest structures and all crop related organisms may be unlikely to find. Various species are dependent on different resources, at different spatial scales and are interacting with several other species. To develop management strategies for increased pollination services, for reduced pest damage or for conservation in the landscape, more species-specific knowledge is needed. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.</p>
39

Macrófitas aquáticas na área de transição entre o rio Areias e o reservatório da Usina Hidrelétrica Luís Eduardo Magalhães - Tocantins: cobertura, biomassa e macroinvertebrados associados

Rodrigues, Úria Graziela Barroso de Souza 16 March 2017 (has links)
Os reservatórios são ambientes aquáticos lênticos de fácil colonização por macrófitas aquáticas, espécies determinantes na dinâmica estrutural de ecossistemas aquáticos. Foi realizada a cobertura e a variação sazonal da biomassa das espécies de macrófitas no trecho de transição entre o reservatório da Usina Hidrelétrica Luís Eduardo Magalhães - Tocantins e o rio Areias, seu afluente, a fim de relacionar estas variáveis com fatores abióticos e o comportamento interespecífico desses vegetais. As coletas foram trimestrais, compreendendo janeiro a outubro de 2016, e demarcados 10 pontos amostrais com 3 repetições. Foram analisadas frequência absoluta, frequência relativa, cobertura relativa, similaridade de Bray-Curtis, biomassa e variáveis abióticas (precipitação pluviométrica, temperatura, oxigênio, transparência, profundidade e pH). Foram amostradas 10 espécies, distribuídas em seis famílias. As espécies mais frequentes foram Najas microcarpa, Oxycaryum cubense e as de maior biomassa foram Oxycaryum cubense e Eichhornia azurea. Salvinia auriculata foi mais frequente no período chuvoso. Os resultados discutidos mostraram que a riqueza (S=10) e a diversidade (H’=1,73) de macrófitas foram mais elevadas no período chuvoso, enquanto a biomassa foi mais elevada no período seco. Os resultados evidenciaram uma estabilidade do reservatório e predomínio de poucas espécies coexistindo no ambiente. / The reservoirs are lentic aquatic environments of easy colonization by aquatic macrophytes, determining species in the structural dynamics of aquatic ecosystems. The cover and the seasonal variation of the biomass of macrophytes species were carried out in the transition stretch between the reservoir of the Luis Eduardo Magalhaes - Tocantins Hydroelectric Power Plant and the tributary river Areias, in order to relate these variables to abiotic factors and interspecific behavior of these vegetables. The collections were quarterly, comprising January to October 2016, and 10 sample points were marked with 3 replicates. Absolute frequency, relative frequency, relative coverage, Bray-Curtis similarity, biomass and abiotic variables (rainfall, temperature, oxygen, transparency, depth and pH) were analyzed. Ten species were sampled, distributed in six families. The most frequent species were Najas microcarpa, Oxycaryum cubense and those with the highest biomass were Oxycaryum cubense and Eichhornia azurea. Salvinia auriculata was more frequent in the rainy season. The results showed that the richness (S = 10) and the diversity (H '= 1.73) of macrophytes were higher in the rainy season, while the biomass was higher in the dry period. The results showed a stability of the reservoir and the predominance of few species coexisting in the environment.
40

Abundância, densidade e efeitos da estrutura da floresta sobre uma comunidade de primatas na fazenda experimental da UFAM, Amazônia Central

Silva, Lívia Rodrigues da 27 March 2013 (has links)
Made available in DSpace on 2015-04-22T22:12:35Z (GMT). No. of bitstreams: 1 Livia Rodrigues da Silva.pdf: 848999 bytes, checksum: 96390303e0c77c713ebc61355dffd413 (MD5) Previous issue date: 2013-03-27 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / Several factors may influence the abundance and density of primate species, mainly those related to forest structure, such as the availability of resources. This study aimed to determine the abundance and density of primate species and their relationships with environmental characteristics and seasonality at Fazenda Experimental da UFAM, Central Amazonia. Diurnal censuses were conducted on 27 1-km transects between November 2011 and October 2012. Data from five components of forest structure were collected in this study: (1) number of trees, (2) number of palms, (3) canopy opening, (4) vertical stratification and (5) fruit availability, measured in 5 plots of 100 m2 located in each transect. We detected seven primate species in 189 km traveled. The estimated density of FAEXP groups were considered intermediate (4.9 groups per km2) than the areas studied and relatively close to the study area. Sighting rates observed in the present study were similar to other areas in the Amazon. Sapajus apella showed the highest rates of sighting and density. The forest structure affected the abundance of two species: Sapajus apella showed a positive association with fruit availability and negatively with the number of palm trees, while Chiropotes chiropotes showed negative relationship with stratification and positively with the number of palm trees. There was no seasonal variation in species abundance, and marginally significant for Pithecia pithecia. The variability on the density of primates found at the study site can be linked to the species biological characteristics, mainly related to the use of food resources. / Diversos fatores podem influenciar a abundância e densidade de espécies de primatas, principalmente àqueles relacionados à estrutura da floresta, como por exemplo, a disponibilidade de recursos. Este estudo teve como objetivo avaliar a abundância, densidade das espécies de primatas e suas relações com variáveis ambientais e sazonalidade na Fazenda Experimental da UFAM (FAEXP), Amazônia Central. Foram realizados censos diurnos em 27 transectos lineares de um km de extensão cada, entre novembro de 2011 e outubro de 2012. Dados de cinco componentes da estrutura da floresta foram coletados neste estudo: (1) número de árvores, (2) número de palmeiras, (3) abertura do dossel, (4) estratificação vertical e (5) disponibilidade de frutos, mensurados em cinco parcelas de 100 m2 localizadas em cada transecto. Foram identificadas sete espécies de primatas em 189 km percorridos. As estimativas de densidade de grupos da FAEXP foram consideradas intermediárias (4,9 grupos por km2) quando comparadas as áreas já estudadas e relativamente próximas à área de estudo. As taxas de avistamento detectadas no presente estudo foram similares às de outras áreas da Amazônia. Sapajus apella apresentou as maiores taxas de avistamento e densidade. A estrutura da floresta afetou a abundância de duas espécies analisadas, Sapajus apella apresentou relação positiva com disponibilidade de frutos e negativa com número de palmeiras, enquanto Chiropotes chiropotes apresentou relação negativa com estratificação e positiva com número de palmeiras. Não houve variação sazonal na abundância das espécies, sendo marginalmente significativo para Pithecia pithecia. A variabilidade na densidade dos primatas encontrados no local de estudo pode estar associada às características biológicas das espécies, principalmente relacionadas ao uso de recursos alimentares.

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